Would it be a safer idea to lance these guys with g rank armor(possibly silver sol Z to give guard+1 )? I tried high rank haku set against black diablos, but got killed in one hit. Or is running around in circles with a hammer the better option(need some getting used to some of his new attacks). Also as much as i love those HBG videos i just down right suck with bow guns XD.
try the barrage / conga / nargax / nargax / nargax - weapon yama hbg on the guide here works for me took me about 3hours practice using heroics but i beat my personal record! my best record for this is 11:49 not as fast as this guy though : http://www.youtube.com/watch?v=ElLIiYfC88w
link to guide http://www.gamefaqs.com/portable/psp/file/943356/56818